Control for air conditioning apparatus

ABSTRACT

A control arrangement for an air conditioning system adapted to serve a plurality of zones, a master control being provided in the control arrangement to energize and deenergize the zone thermostats, the master control energizing the individual zone thermostats in response to a preselected temperature variation from the zone thermostat set point in a respresentative zone, deenergization of the zone thermostats by the master control allowing the temperature in each of the zones to increase or decrease from the zone thermostat set point and reduce the load on the air conditioning system for weekend and nighttime operation.

United States Patent 1 Wood [ Dec. 11, 1973 CONTROL FOR AIR CONDITIONINGAPPARATUS 75 Inventor: Russell 1:. Wood, Syracuse, N.Y. [73] Assignee:Carrier Corporation, Syracuse, NY.

[22] Filed: June 5, 1972 [21] Appl. No; 259,888

Related U.S. Application Data [62] Division of Ser. No. 139,090, April30, 1971, Pat.

UNITED STATES PATENTS 3,051,451 8/1962 Bierwirth et al. 165/22 3,116,7861/1964 Mewditch 165/22 Primary Examiner-Charles Sukalo Attorney-J.Raymond Curtin [571 ABSTRACT A control arrangement for an airconditioning system adapted to serve a plurality of zones, a mastercontrol being provided in the control arrangement to energize anddeenergize the zone thermostats, the master control energizing theindividual zone thermostats in response to a preselected temperaturevariation from the zone thermostat set point in a respresentative zone,deenergization of the zone thermostats by the master control allowingthe temperature in each of the zones to increase or decrease from thezone thermostat set point and reduce the load on the air conditioningsystem for weekend and nighttime operation.

2 Claims, 3 Drawing Figures CONTROL FOR AIR CONDITIONING APPARATUS Thisis a division, of application Ser. No. 139.090 filed Apr. 30, l97l nowUS. Pat. No. 3,709,769 granted Jan. 9, 1973.

BACKGROUND OF THE INVENTION To reduce the operating costs of an airconditioning system, it is desirable to reduce the load on the systemwhen the building served thereby is not in use. In most instances, thiswould ordinarily entail a temperature reduction at night and on weekendsduring the heating season and a temperatureincrease at night and onweekends during the cooling season.

In air conditioning installations serving a plurality of zones whereineach zone is provided with a thermostat to maintain the desiredtemperature in the zone, each zone thermostat may be manually adjustedto provide the desired temperature increase or decrease at night and onweekends. However, this is time consuming. Further, the thermostats mustbe reset to the desired temperature a number of hours before thebuilding is to be occupied to allow time for the air conditioning systemto increase or decrease the zone temperatures to the desired level.

SUMMARY OF THE INVENTION This invention relates to a control arrangementfor an air conditioning system serving a plurality of zones, each zonebeing provided with athermostat to maintain the desired temperature inthe zone served thereby. A master thermostatic control means, responsiveto the temperature in a zone having heat gains and heat lossesrepresentative of the heat gains and heat losses in the remainder of thezones, whenactuated, deenergizes the individual zone theremostats whenthe temperature of the representative zone is at a predeterminedtemperature variation from the zone thermostat set point, the masterthermostatic control means energizing each of the zone thermostats whenthe temperature of the representative zone decreases below thepredetermined temperature during the heating season or when thetemperature of the representative zone increases above the predeterminedtemperature during the cooling season.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an airconditioning apparatus with portions of the cover broken away toillustrate internal components;

FIG. 2 is a view partly in section and partly in elevation of theapparatus of FIG. I; and

FIG. 3 is a schematic view of the control system for the airconditioning apparatus of FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, thereis illustrated an air conditioning apparatus adapted to serve aplurality of zones in a building to provide individual temperaturecontrol in each zone. A plurality of direct-fired heat exchangers 2 forheating air and a plurality of refrigerant coils 4 are provided. A fan 6and fan motor 7 are provided to circulate air over the evaporator coilsand heat exchanger. Suitable switch means 8 (FIG. 3) are provided tocomplete the electrical circuit to fan motor 7 to energize the motor.

The unit illustrated is adapted to serve up to five individual zones. Toaccomplish this, baffles 9 are located to provide five separate airpassages downstream from fan 6. Each passage contains a singlerefrigerant evaporator coil 4 and two direct fired heat exchangers 2.While a single evaporator coil and two direct-fired heat exchangers areillustrated in each air passage, it should be understood that anydesired number of evaporator coils 4 and heat exchangers 2 could belocated in each passage formed by baffles 9. Further, electricresistance elements or other well-known types of heating means could beemployed in place of the direct-fired heat exchangers 2. Each airpassage is provided with a discharge opening 10, only one of which isvisible in FIG. 2.

The conditioned air from each discharge opening 10 may be supplied tothe individual zone to be served thereby. While each passage containingan evaporator coil 4 and two heat exchangers 2 may serve a single zone,in many applications a number of discharge openings may be connected toa common duct to serve a zone requiring a greater heating and coolingcapacity than could be provided by a single evaporator coil and two heatexchangers.

Each heat exchanger 2 is provided with a fuel burner 12 and a fuel valve14 adapted for energization by thermostatic control means located ineach zone served by the air conditioning apparatus.

A refrigerant compressor 16 and a condenser 18 are provided to supplyliquid refrigerant to the evaporator coils 4. Each evaporator coil 4 isprovided with a refrigerant liquid line solenoid valve LLS (FIG. 3) tocontrol the flow of refrigerant from the condenser 18 to the coils. Theliquid line solenoid valves LLS are also controlled by thermostaticcontrol means located in each zone served by the air conditioningapparatus. Fan means 20 are provided to circulate ambient air overcondenser 18 to condense the refrigerant therein.

Air from the individual zones is returned to the apparatus throughopening 22 into a chamber 24. Fan 6 draws air from chamber 24 throughfilters 37 for passage over heat exchangers 2 and evaporator coils 4prior to passage to the individual zones.

FIG. 3 illustrates the-control arrangement for the aforementioned airconditioning apparatus for an installation where the apparatus isadapted to serve five zones, each zone being served by a singleevaporator coil 4 and the two heat exchangers 2 associated therewith.

Thermostatic control means 15, including a temperature responsive switch40 and a temperature responsive switch 42 are disposed in each zoneserved by the air conditioning apparatus. The thermostatic control means15 are connected in control circuits provided with 24 volt current bytransformers 48 and 49. The thermostatic control switches 40 are adaptedto energize control relays A/2, B/2, C/2, D/2, and E/2. Relay A/2 isprovided with switches A1 and A2, relay 8/2 is provided with switches B1and B2, relay C/2 is provided with switches C1 and C2, relay D/2 isprovided with switches D1 and D2 and relay E/2 is provided with switchesE1 and E2. Each of the temperature responsive switches 42 is adapted toenergize the gas valve 14 associated therewith.

When heating is required in a zone served by one of the thermostaticcontrol means 15, the heating-cooling switch 50 associated therewith ismoved to the heating position as illustrated by the dotted line toprovide current to thermostatic switch 42. Upon a drop in the tem- Vperature of the zone, switch 42 will close to provide current to the gasvalve 14 associated therewith and provide gas to the burners serving thezones to provide heat thereto.

When cooling is required in one of the zones served by the airconditioning apparatus, the heating-cooling switch 50 associated withthe zone will be positioned as shown by the solid line to providecurrent to thermostatic switch 40. Upon a rise in temperature of thezone, the switch 40 will close to provide current to the relayassociated therewith. Energization of the relay will cause the switcheswithin the relay to close, thereby providing current to the liquid linesolenoid valve associated therewith to open the valve and allow passageof liquid refrigerant from condenser 18 to the coil 4 serving the zone.Relays Fl 1 and G/] will also be energized by the closing of the relayswitch; energization of relay F/l closing switch Fl associated therewithto energize the compressor 16, energization of relay G/l closing switchG1 to energize condenser fans 20. Thus, upon a demand for cooling in anyof the zones served by the apparatus, the compressor and condenser fanwill be energized and the liquid line solenoid valve (LLS) associatedwith the zone will be opened to allow passage of liquid refrigerant fromthe condenser to the evaporator coil 4 serving the zone.

During periods when the building is not in use; such as nights andweekends, it is desirable to reduce the load on the air conditioningsystem. This may be accomplished during the heating season by allowingthe temperature of the zones to drop below the normal temperaturemaintained in the zones and during the cooling season by allowing thetemperature of the zones to rise above the normal temperature maintainedin the zones. To accomplish this, a suitable master thermostatic control54 is provided within a zone served by the apparatus having heat gainsand heat losses representative of the heat gains and heat losses in theremainder of the zones. The master thermostatic control 54 is providedwith thermostatic switches 56 and 58 and a heat-cool switch 60. A nightset back switch 62 is provided for reasons to be hereinafter explained.During normal daytime, operation, switch 62 is positioned as shown bythe solid line to bypass thermostatic control 54, thereby providingcurrent to the temperature responsive means serving the zones. Theswitch 62 may be manually controlled or may be controlled by suitabletimer means to automatically move the switch between the solid lineposition and the dotted line position on a preselected time schedule.

When switch 62 is in the position illustrated by the dotted lines,thermostatic control 54 is placed in the control circuit for the airconditioning system. When heating is required in the zone containingthermostatic control 54, the heating-cooling switch 60 is moved to theheating position as illustrated by the dotted line to provide current tothermostatic switch 58. Switch 58v will be adjusted to open at apreselected temperature below the temperature at which the thermostaticswitch 42 is located within the same zone will open. Thus, when switch62 is in the position illustrated by the dotted line, the thermostaticswitch 58 will open the electrical circuit to all of the thermostaticcontrol means 15 to prevent operation of the heating means or thecooling means unless the temperature of the zone 4 containingthermostatic control 54 drops below the preselected temperature.

When cooling is required in the zone containing thermostatic control 54,the switch 60 will be positioned as shown by the solid line to providecurrent to thermostatic switch 56. Thermostatic switch 56 will beadjusted to close at a preselected temperature above the temperature atwhich the thermostatic switch 40 in the zone containing thermostaticmeans 54 is set. Thermostatic switch 56 will thus open the circuit toall of the thermostatic control means 15 unless the temperature in thezone containing thermostatic control 54 increases to the preselectedtemperature at which switch 56 closes. Upon the closing of switch 56,current will be provided to all the thermostatic control means 15.

It can be seen from the foregoing that the thermostatic control means54, when energized by switch 62, will maintain the zone containingthermostatic control means 54 at a pre-selected temperature above thenormal zone temperature when the zone requires cooling and maintain thezone at a preselected temperature below the normal temperature when thezone requires heating. Since thermostaic control means 54 energizes anddeenergizes the thermostatic control means located in all the zonesserved by the air conditioning apparatus, and the heat gains and heatlosses in the zone containing thermostatic control means 54 arerepresentative of the heat gains and heat losses in the remaindingzones, thermostatic control means 54, by energizing and deenergizing thethermostatic control means 15, will allow the temperature in theremaining zones to increase above the normal temperature when the zonesrequire cooling and decrease below the temperature when the zonesrequire heating.

It should be understood that during the intermediate seasons, a numberof zones may require cooling and a number of zones may require heating.When thermostatic control 54 energizes the zone thermostats, each zonethermostat set for cooling operation will energize the cooling coilassociated therewith if the temperature of the zone is above the zonethermostat set point, while the zone thermostats set for heating willenergize the heating elements associated therewith if the temperature ofthe zone is below the zone thermostat set point.

When the thermostatic control 54 is satisfied, all of the zonethermostats will be deenergized.

The temperature of the representative zone will be maintained at the setpoint of thermostat control 54 when control 54 is energized. Since thecontrol 54 is responsive to the temperature in a representative zone,the temperature in the remainder of the zones will vary from the zonethermostat settings to a degree approximating the temperaturedifferential between the set point of thermostatic control 54 and theset point of the zone thermostat in the representative zone.

While I have described a preferred embodiment of my invention, it is tobe understood that my invention is not limited thereto but may beotherwise embodied within the scope of the following claims:

I claim:

1. A method for controlling an air conditioning system serving aplurality of zones comprising the steps of:

providing heated air to the zones requiring heating and cool air to thezones requiring cooling in response to temperature control means locatedin each zone served by the air conditioning system,

zone is below the predetermined temperature and the representative zonerequires heating.

2. A method for controlling an air conditioning system according toclaim 1 further including the step of energizing the temperatureresponsive means in each zone when the temperature of the representativezone is above the predetermined temperature and the representative zonerequires cooling.

1. A method for controlling an air conditioning system serving aplurality of zones comprising the steps of: providing heated air to thezones requiring heating and cool air to the zones requiring cooling inresponse to temperature control means located in each zone served by theair conditioning system, deenergizing the temperature control means ineach zone in response to a predetermined temperature in a zone havingheat gains and heat losses representative of the heat gains and heatlosses in the remainder of the zones to allow the temperature of eachzone to vary from the temperature set point of temperature control meanslocated therein; and energizing the temperature responsive means in eachzone when the temperature of the representative zone is below thepredetermined temperature and the representative zone requires heating.2. A method for controlling an air conditioning system according toclaim 1 further including the step of energizing the temperatureresponsive means in each zone when the temperature of the representativezone is above the predetermined temperature and the representative zonerequires cooling.